1. Field of the Invention
The present invention relates to an image processing apparatus, and particularly relates to an image processing apparatus for obtaining image data to be output, by subjecting, to predetermined image processing, image data obtained by photoelectrically reading an image recorded on a photographic film.
2. Description of the Related Art
In recent years, a technique has been known with which frame images recorded on a photographic film are photoelectrically read by a reading sensor such as a CCD. Digital image data obtained by the reading operation is subjected to image processing including enlargement/reduction and various correction processes. Then, a laser beam modulated in accordance with processed digital image data is used to form an image on a recording material.
In the technique for digitally reading frame images by using a reading sensor such as a CCD, in order to realize accurate image reading, a frame image is read (performing so-called xe2x80x9cprescanxe2x80x9d). Thus, reading conditions (for example, the amount of light with which the frame image is illuminated and charge storage time in the CCD) corresponding to, for example, the density of the frame image are determined. Under the decided reading conditions, the frame image is again read (so-called xe2x80x9cfine scanxe2x80x9d).
A frame image photographed by a lens-fitted film package or a film with a lens becomes distorted, as shown in FIG. 8A. The distortion is caused by the distortion aberration of the photographing lens provided in a camera. The degree of the distortion of the image varies depending on the type (for example, the model, the trade name, the telephoto lens, or the wide angle lens, and the like) of the photographing lens. That is, the amount of the distortion aberration varies depending on the type of the photographic lens. If the amount of the distortion aberration is great, distortion of the image is enlarged. If the amount of the distortion aberration is small, distortion of the image is reduced. If the frame image recorded on a photographic film is distorted, reading of the frame image and using read image data to form an image on a recording material result in formation of an image having distortion.
An image processing apparatus has been disclosed with which information about the type of the photographing lens provided for a camera is obtained in advance. In accordance with the obtained information, digital image data is subjected to an image process (correction of distortion aberration) (refer to Japanese Patent Application Laid-Open (JP-A) Nos. 9-281613, 6-250276, 6-250277, 6-237376, 6-236004 and 6-165024). The distortion aberration correction is a process for correcting distortion of the image caused by the distortion aberration of the photographing lens. Since the distortion aberration correction is performed as described above, digital image data which must be output can be obtained. Digital image data which must be output is used to form an image on a recording material. As a result, an image free from distortion can be formed on the recording material.
However, when an image is formed on a recording material by using digital image data which has been subjected to the correction of distortion aberration and which must be output, uncertain pixels are formed in the periphery of the image, as shown in FIG. 8B. This leads to a fact that an image with edges is undesirably formed on the recording material. Therefore, the following process is usually performed: pixels (in a range indicated with arrows G shown in FIG. 8B) in the periphery having uncertain pixels are out. Then, only pixels on the inside are used to form an image. A region, the image of which has not been formed on the recording material due to the cutting operation, is called an missing image region. If an important object is photographed on the periphery of this missing image region, the foregoing method results in the fact that the important object is not reproduced on the recording material. Therefore, the foregoing method sometimes leads to problems. If an image of a group of persons or the like, in which persons are in the overall region, is formed, person in a corner is sometimes not reproduced on the recording material.
When digital image data, which must be output and which is obtained by subjecting digital image data obtained by reading a frame image to correction of distortion aberration in accordance with information about the photographing lens, is used to form an image on a recording material, an image having uncertain pixels in the periphery is undesirably formed. That is, there arises a problem in that the image formed on the recording material has a missing image region.
To overcome the above-mentioned problem, an object of the present invention is to provide an image processing apparatus which is capable of preventing missing image regions caused by execution of the correction of distortion aberration.
To achieve the foregoing object, according to a first aspect of the present invention, there is provided an image processing apparatus comprising: determining means for determining whether or not image data obtained by reading an image recorded on a photographic film must be subjected to distortion aberration correction for correcting distortion of an image caused by distortion aberration of a photographing lens employed when the image is recorded on the photographic film; and reading-range setting means for setting an image reading range to be substantially the same as a range for use as an output image when a determination has been made by said determining means that the distortion aberration correction is not required and for setting the image reading range to be a range larger than the range for use as the output image by a predetermined amount when a determination has been made that the distortion aberration correction must be performed.
The image processing apparatus according to the first aspect incorporates the determining means for determining whether or not image data obtained by reading an image recorded on a photographic film must be subjected to the distortion aberration correction, which is an image process. The distortion aberration correction is a process for correcting distortion of an image caused by distortion aberration of the photographing lens employed to record the image on the photographic film. The determining means is able to make the determination in accordance with information about the photographing lens. For example, camera type identification information for identifying the type of the camera used in photographing the image (including cases in which information expressing that photography was carried out by using a lens-fitted film package is recorded on the photographic film) may be used as the information about the photographing lens.
The image processing apparatus according to the first aspect incorporates the reading-range setting means for setting the image reading range recorded on the photographic film. The reading-range setting means sets the image reading range in accordance with a result of the determination made by the determining means. If the determining means determines that image data obtained by reading the image recorded on the photographic film does not require to be subjected to the distortion aberration correction, a range substantially the same as the range for use as the output image is set as the image reading range. If the determining means determines that the distortion aberration correction must be performed, a range larger than the range for use as the output image by a predetermined amount is set as the image reading range. Note that the output image includes an image recorded on a recording material such as a light-sensitive material, an image displayed on display means such as a monitor, and an image stored in an information recording medium.
The set image reading range is read, and then image data obtained by subjecting the read image data to the distortion aberration correction is used to obtain an output image. Thus, missing image regions in the output image can be prevented.
A second aspect has a structure according to the first aspect, further comprising lens-information obtaining means for obtaining information about the photographing lens, wherein when said determining means has determined that the distortion aberration correction must be performed, said reading-range setting means obtains a range which can be used as an output image on an image indicated with image data subjected to the distortion aberration correction performed in accordance with information about the photographing lens obtained by said lens-information obtaining means and calculates and sets an image reading range in accordance with the size of the usable range.
The image processing apparatus according to the second aspect incorporates the lens-information obtaining means for obtaining information about the photographing lens employed when the image has been recorded on the photographic film. Information about the photographing lens includes, for example, the model number, the trade name, information about the photographing lens, such as a telephoto lens or a wide angle lens. The lens-information obtaining means may have a structure where a lens identification code in the form of a bar code or the like is previously formed on the photographic film so as to be read by a sensor. If the photographic film is an APS film, lens identification data is magnetically recorded on a magnetic recording layer when the image has been photographed so as to be read by a magnetic head.
The reading-range setting means provided for the image processing apparatus according to this embodiment, when the determining means has determined that the distortion aberration correction must be performed, obtains a range which can be used as an output image on an image indicated with image data subjected to the distortion aberration correction performed in accordance with information about a photographing lens obtained by the lens-information obtaining means and calculates and sets an image reading range in accordance with the size of the usable range. Specifically, the reading range can be calculated in accordance with the ratio of the size of the range which can be used as the output image on the image indicated with image data before the distortion aberration correction and the size of a range which can be used as the output image on the image indicated with image data subjected to the distortion aberration correction.
In a third aspect of the present invention, the image processing apparatus according to the first aspect further comprises a lens-information obtaining means for obtaining information about the photographing lens. The reading-range setting means stores in advance reading ranges of images in correspondence with a plurality of information on photographing lenses. When the determining means determines that distortion aberration correction must be performed, the reading-range setting means reads and sets an image reading range which corresponds to the information on the photographing lens obtained by the lens-information obtaining means.
The image processing apparatus according to the third aspect comprises the lens-information obtaining means for obtaining information about the photographing lens, i.e., for obtaining information about the photographing lens employed at the time the image is recorded on the photographic film. The reading-range setting means provided at the image processing apparatus has stored in advance image reading ranges corresponding to respective information on a plurality of photographing lenses. When the determining means determines that distortion aberration correction must be carried out, the reading-range setting means reads and sets an image reading range which corresponds to the information on the photographing lens obtained by the lens-information obtaining means. As a result, when the distortion aberration correction is performed, simply reading previously stored information allows setting of the image reading range. Therefore, the number of processings required can be reduced.
Here, the reading range is the scan range of the photographic film which is read by the image reading means which reads images recorded on photographic films.
Further, when the image reading means is an area sensor for reading the image in areas, the reading-range setting means may change the scan range by changing the optical magnification of the area sensor. In this case, when the determining means determines that distortion aberration correction must be performed, the reading-range setting means may set the optical magnification to a predetermined fixed value such that the reading range of the image is a range which is larger, by a predetermined amount or more, than the range used as the output image.
When the image reading means is a line sensor for reading the image in lines, the reading-range setting means may change the scan range by changing at least one of the optical magnification and the subscanning range of the line sensor. In this case, due to the reading-range setting means changing the optical magnification of the line sensor, the scan range can be changed. When the determining means determines that the distortion aberration correction must be performed, the reading-range setting means may set the optical magnification to a predetermined fixed value such that the reading range of the image becomes a range which is larger, by a predetermined amount or more, than the range used as the output image.
This xe2x80x9creading rangexe2x80x9d is not limited to the scan range of the photographic film read by the reading means. A storing means for storing image data obtained by the reading of the image recorded on the photographic film may be provided, and the reading range may be a range of image data read from the storing means.
A changing means for changing the electronic magnification may be provided in order to have the output image be a predetermined size.